Genetic Information and Variation Flashcards
(Only classification and Biodiversity) (40 cards)
Define a species
a group of organisms which share common traits and are able to reproduce to produce living, fertile offspring.
Talk about the Binomial Naming System and how it came about.
At one time. scientists named species depending on their features which resulted in different species coming under the same name.
LINNAEUS- developed the binomial naming system to overcome this featuring:
Generic Name- denotes the genus of the organism
Specific Name- Denotes the species of which the organism comes from and isn’t shared by other organisms in the genus
What is Courtship Behaviour?
This is the method so that members of the same species can reconise one another allowing them to mate and produce viable offspring and pass on their genes. They are complex displays that (usually men do) to attract (the females)
During courtship behaviour, animals use signals to communicate with a protenrial mate and members of the same sex. There is a series of actions and responses stimulating further action. This is called a stimulus response chain.
Why is Courtship behaviour needed?
- To recognize members of their own species in order to create fertile offspring
- Synchronise mating to a time when females are producing eggs.
- To form a pair bond and ensure mating is successful
- to identify a mate who is able to breed and is fertile and sexually mature.
What is Classification and the two types?
Classification is the grouping of oraganisms into manageable groups.
Artificial- This divides organismes according to differences at the time. These may be things like colour and size.
Phylogenic- is based on evolutionary relationships between organisms and their ancestors using shared features. It arranges them in a hierarchy with no overlap
What is Taxonomy and a Taxa?
TAXONOMY- the study of the groups of biological classification and their positions.
TAXA- closely related organisms are grouped together into groups called taxas. Each taxon is arranged into a hierarchy. its divided into smaller more specific taxas at each level. There is no overlap between taxa at the same level.
A domain is the highest Taxa.
What are the three domains?
Bacteria- Group of single celled prokaryotes with an absence of membrane bound organelles with smaller ribosomes and murein cell walls
Archaea- group of single celled prokaryotes that were origionally classified as bacteria which they resemble in appearance. They differ from bacteria because their genes and protein synthesis are more similar to eukaryotes and there is no murein in their cell walls,
Eukarya- group of organisms made up of one or more eukaryotic cells. They have got membrane bound organelles like mitochondria and chloroplasts and larger ribosomes. This is divided into:
Protoctista, Fungi Plantae and Animalia.
What is the order of classification?
Kingdom
Phylum
Class
Order
Family
Genus
Species
Describe Phylogeny.
Phylogeny is the evolutionary relationship of an organism or group of organisms.
it is based on the fact that all organisms share a common ancestor and more closely related organisms will share more recent common ancestors.
What does a phylogenic tree show?
A phylogenic tree shows the evolutionary relationship between different species and their most recent common ancestor. Each branch shows a different species and the point at which they join together is the common ancestor of the two species.
What is Biodiversity?
general term used to describe variety in the living worlds. It refers to the number and variety of living organisms in a particular area
What’s the difference between Species Diversity and Genetic Diversity?
Species Diversity- Number of different species and the number of individuals of each species within one community
Genetic Diversity- variety of genes possessed by the individuals that make up a population of a species.
What is species richness?
This is the number of different species in a particular area at a given time.
Two communities may have the same number of species but the proportions of the community made up of each species may differ markedly.
How does agriculture effect the biodiversity of an area?
Agricultural ecosystems reduce the biodiversity and the number of species present because humans select for particular characteristics thus reducing the number of alleles and therefore the genetic diversity of the population.
Monoculture Farming-only using a single species of crop on a field. this therefore means that fewer individuals of other species can survive there
How do we maintain biodiversity through agriculture?
- Using hedgerows insulted of fences
- Growing different crops in the same area known as intercropping
- reducing the uses of herbicides and pesticides
- preserving wetlands
Talk about Hedgerows.
Many Traditional mixed farms require hedgerows to contain livestock and act as a barrier, however, as many farms have been converted to large, monoculture arable farms, fields need to be larger to accomodate a maximum amount of crops and the large machinery.
In Britain, this has led to the loss of thousands of kilometers of hedgerow each year. A threat to them is also neglect and improper management which is resposnible for for almost half the loss. In 1997, legislation was introduced to control the destruction meaning land owners must apply to remove a section of hedgerow over 20 meters.
They are important because:
- support up to 80% of Englands Birds, 50% of mammels and 30% of butterflies
- Ditches and banks associated with hedgerows provide habitat for amphibians and reptiles.
- Provide nesting material and food for birds
- Act as corridors along which animals can safely move
- Barriers for windborne pests
- Reduce wind speed to prevent erosion
How and why do we investigate biodiversity?
Comparing genetic diversity within and between species helps scientists to determine the evolutionary relationships between them.
- Comparison of Observable Characteristics
- Comparison of DNA base sequences
- Sequence of Amino Acids
Talk about the Comparison of Observable Characteristics
Traditionally, genetic diversity was measured by observing the characteristics of organisms. It is based on the fact that each observable characteristics are determined by a gene or genes.
However, this has many limitations such as :
- the characteristics could be coded for by more than one gene
- The same characteristic could have arisen sepeartly
- The characteristics could be influenced by the environment and the not the genes.
Talk about the comparison of DNA base sequences
With the introduction of gene technology, we can now read the base sequences of the DNA of any organism. Using techniques, they can determin the exact order of nucleotides on DNA by dying them with flouresent dye which produces a serous of coulourded bands. Here, we can measyre abd sequence it to produce a pattern of colourded bands. Analysing these pattersn allows us to compare species with each other. This can also be done with mRNA
However, due to mutations, the sequences of nucleotide bases of the new species will change. Overtime, more and more mutations lead to the creation of new species.
Talk about the sequence of amino acids
this can be taken back to the mRNA
sequence and thus the DNA sequence. The differences between species are called interspecific
variation. There are also differences between individuals of the same species which is known as
intraspecific variation.
Talk about genes.
A gene is a base sequence of DNA that contains the coded information for making functional RNA and polypeptides. The information is in the form of a specific sequence of bases along the DNA molecule.
A gene occupies a fixed position called a locus.
The amino acid sequence of a polypeptide: polypeptides make up proteins, therefore genes determin the proteins of an organism- enzymes are proteins that control chemical reactions therefore genes are responsible for the development of organisms
Talk about the genetic code
The genetic information is therefore stored as a three-base sequence called a triplet. The order of these bases is called the genetic code. Each codon represents one of 20 amino acids which is effectively universal, being the same in all living things. It codes for a specific amino acid.
The code is also degenerate meaning more than one codon codes for each amino acid. This also reduces the amount of mutations
The code is also non-overlapping, each base in a gene is only part of one triplet of bases and each base is only read once
The amino acids are then joined by peptide bonds and form a polypeptide chain.
Talk about evidence for the three base theory.
The genetic code is the code our body uses to convert the instructions contained in our DNA. It is the order of bases on DNA
Scientists suggested that there must be a minimum of three bases that coded for each amino acid due to the fact that:
- There are only 20 different amino acids
- Each amino acid must have its own code
- Only 4 different bases in DNA
- if each base coded for a different amino acid, there will only be 4
- Using a pair of bases = 4 squared which is 16 which is too little
- by using 3 it would be 64 different codes which is more than enough
Talk about non coding and coding regions of DNA
Much of the DNA in eukaryotes doesnt code for polypeptides, between genes there are non-coding sequences made up of multiple repeating base sequences between genes called introns. Even with a gene, only some sequences, exons, code for amino acids.
